“I have not failed. I’ve just found 10,000 ways that won’t work.” ~Thomas Edison

At my real-pay-me-to-solve-problems job, failure happens from time to time. As an engineer it’s important to recognize when a problem can’t be solved in a reasonable manor. Obviously the more important the problem, the higher the criteria for “reasonable”. It’s not surprising to me that some of my hobby projects don’t work out. Heck, it would be boring if everything just worked. I’ve decided to share this learning experience with others.

The goal of this project was to design a card shuffling machine. The topic came up when a friend informed me that there are two categories of shuffling devices on the market. The cheap $20 plastic shufflers you can find at Target, and the $1500+ professional solutions. Both systems are fairly controlled systems, and I thought it would be more interesting to take a Rube Goldberg approach. My card shuffling machine used physical environmental factors (ie air flow) to randomize the cards. In a nutshell my idea was to use a big fan to blow a deck of cards around in a box similar to how those bingo or Powerball lottery machines work. Then after the cards had been randomized I’d have a series of shoots, doors and sensors to get all the cards face down in a nice stack.

I made a prototype of what I thought would work. Here is a video describing how it works.

To get things working reliably I’d need to do a few more iterations of the slides and figure out how to make a small, powerful and cheap fan. I have ideas on how to get around all my known problems, but I believe solving all the problems could turn into a much bigger effort than I had expected when I started this project. Basically I’ve decided I’m not interested enough in this problem to work through these problems I’ve found.

I have a lot of other things I’d like to work on so instead of focusing on this project, I’ve decided to cut my losses and move on to other things. If anybody else decides to pick up this project and improves on it let me know. I’d love to hear about any related past or future projects. I was surprised that my google searches didn’t turn up any projects like this.

8 Comments

James S said,

I’ve pondered making such a machine myself. I think I have a solution for your air shuffling. Instead of using one board with a bunch of holes, create a single jet of forced air from the very bottom of that ramp. Hopefully it creates a vortex in the process. Otherwise really cool.

AnimeEd said,

You’ll probably find that the single card releasing mechanism is the most difficult thing to perfect. In fact, I would be surprised if you got it to work for a whole stack. Paper handling is not an easy task.

Glacial Wanderer said,

I didn’t expect many people to read this post since it didn’t work so I didn’t do a very thorough writeup. Let me list the problems I saw and make some comments.

1) I claimed that the fan was underpowered. This isn’t entirely true. If the fan moved 500 cubic feet of air a minute as advertised I’d have over 30 mph wind and that would be more than enough to blow the cards around. The problem is that airflow is restricted at certain points. One of those is the is the vent. I did try taping up some of the holes and it did not help. I actually found that removing the vent entirely gave the best performance, but it was still not good enough. I think an aerospace engineer could calculate why the observed airflow is so much less the theoretical max, but I can’t. All I know is I was hoping for 10%-20% drop and I’m probably seeing 70-80%. As it stands the cards get blown around as long as they are perpendicular to the airflow they get blown around, but if they turn sideways they fall and get stuck at the bottom. One person on my website suggested using compressed air and I like that idea, but it would increase the cost. I also think replacing the fan entirely with a spinning plexiglass cube might be a good solution.

2) I completely agree with those above that a webcam could easily detect if a card is upside down. However, I was planning to go a cheaper route. I was planning to use just an Arduino and no PC. I know if I put a black dot on one side of the cards I could reliably detect that dot with IR sensor. I think I could have also probably used a specialized clear IR paint. Another option would be to find a deck of cards that allowed the IR sensor to work without modifying the cards. I am pretty sure this problem is easy to solve so I was saving it to last.

3) Cards sometimes randomly got stuck in the slide system. There is a chance that adding paint and sanding would make the slides slippery enough so this didn’t happen, but I suspect I would have needed to do some minor tweaks to the slide system. By tweaks I mean change slide positions and angles.

4) I hadn’t hooked up the servos so I don’t know if there would have been a problem with selecting a single card. My hunch is that there would be a problem here and I’m not sure of an easy way to solve this one. My best bet would be buying those slightly thicker plastic cards.

Gordie said,

I would make the card separator more like a printer paper feeder. A rubber roller pushes the sheets (cards) past an inclined rubber pad. The edges of the sheets get stuck on the pad unless they are touching the wheel which is a little ‘stickier’ than the pad. A pair of pinch rollers (synchronized to the first roller) pull the last little bit out from under the pad. Depending on how slow the rollers are going you’d probably have enough time to recognize orientation and shift the ‘flipper’ without a second gate.

Regarding recognition of orientation, use cards with a blue back and illuminate it with a blue led. The back should look blank or nearly so to the detector while the front will have dark spots.

Regarding the airflow, I am assuming the ‘vent’ is the piece of wood with all the holes in it. Try making the holes bigger or closer together and only the bottom half or two thirds of the ramp. Put a row of holes on each side just above the vent plate so that any cards that fall down along the walls will get the bottom edge pushed back into the flow stream. Also, if you hook up the fan to suck air out of the top you won’t need to run pipes to the side jets and if painting the slides doesn’t help you could turn them into little air hockey tables.

BTW What happens when the cards get turned crossways?

Gordie

Glacial Wanderer said,

Gordie, I like you idea for selecting the top card. I did try making the vent holes bigger and I tried taping some of the holes at the top. Neither of these helped much. I think I need a much bigger fan.

A card can’t get sideways due the way the machine is designed. I supposed if my fan was more powerful I could have problems with that at the top, but I think pulsing the fan would get stuck cards unstuck. I could also alter the geometry of the clear box on top top to minimize this problem if needed.